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Human Swine influenza: the Australian perspective Print E-mail
The Quarterly 2011

 


This article was written by Dr Susan Keam, derived from material presented by Dr Bernard Street on 6 September 2010 at RACMA/HKCCM 2010.

In 2009 Australia experienced an outbreak of H1N1 influenza, commonly known as "Swine flu". This was part of a worldwide Swine Flu pandemic, declared as such by the WHO on 11 June 2009.

Influenza viruses are part of the orthomyxidiae family and are RNA enveloped viruses. Swine influenza virus (SIV) is any strain of the influenza family of viruses that is endemic in pigs. As of 2009, the known SIV strains include influenza C and the H1N1, H1N2, H3N1, H3N2 and H2N3 subtypes of influenza A.

Historically, influenza pandemics are associated with a novel (new to humans) influenza A virus strain that can cause disease and be spread by person-to-person transmission. Such epidemics have occurred every 10-50 years. In the 20th century there have been three pandemics:

  • The 1918/1919 (Spanish Flu) pandemic was a H1N1 mutation from an avian strain. This was a devastating pandemic causing an estimated 50 to 100 million deaths
  • The 1957 (Asian Flu) pandemic was a H2N2 mutation originating in China from an avian strain. This pandemic resulted in an estimated 1 million deaths.
  • The 1968 (Hong Kong Flu) pandemic was a H3N2 mutation from an avian strain. It caused an estimated 1 million deaths.

Because of the potential high mortality, pandemic influenza is a major issue being addressed by the World Health Organisation and regional health authorities. Planning in Australia includes accurate polymerase chain reaction (PCR testing), public health surveillance, a graduated response plan, improved infection control, treatment of patients and provision of anti virals and vaccinations.


The Australian Health Management Plan for Influenza

Within this plan are a number of phases for managing a pandemic, based on the WHO classifications. These range from ALERT and DELAY before the virus has reached Australia and, once the virus has hit the country, progress through CONTAIN, SUSTAIN, CONTROL AND RECOVER. As a point of reference there are, on average, 2000 to 3000 deaths every year as a result of seasonal influenza in Australia. When discussing H1N1, we need to keep in mind the background level of influenza mortality.

Preparedness for managing a pandemic in Australia occurs at a Federal level and at State and Territory level. The structure responsible for Australian flu pandemic planning includes the Australian Health Minister’s Advisory Committee, the Australian Health Protection Committee, the Office of Health Protection and CMO Expert Advisory Group. In addition there are a number of joint national and jurisdictional bodies that take responsibility for administering the plan. The decision-making structure for managing a pandemic in Australia consists of the Australian Government Infectious Diseases Committee, the CMO Expert Advisory Group, the Australian Health Protection Committee, Communicable Diseases Network Australia and the State and Territory governments. Having this structure in place and ready to respond put Australia in a good position when the flu pandemic occurred in 2009.


The Australian Experience

The first case of swine flu in Australia occurred in a 33-year-old woman who touched down in Brisbane on a flight from Los Angeles on 9 May 2009. Community anxiety was very high. Following this, there were a number of other cases, and at one stage a ship visiting Queensland was quarantined.

The first case in the state of Victoria was an 11-year-old boy, and later his two brothers, from Clifton Hill Primary School. The school was closed for eight days. Shortly after, there were outbreaks recorded at two other schools in Victoria. Victoria then went onto a MODIFIED SUSTAIN PHASE; although there were a number of swine flu cases reported, virulence of the disease varied (e.g. pregnant women with swine flu were severely affected and many required admission to ICU while other patient group had only mild disease). A communiqué from the Health Department on 10 June 2009 was issued in which patients who thought they had swine flu were asked to present to their GP first, and to only present to hospital if they were seriously ill.

There were a number of case definitions to guide health professionals in assessing Swine Flu disease severity. These included: fever = 38.5 C (or a significant history of fevers e.g. rigors) and two or more of the following - cough, sore throat, body aches, myalgia, fatigue, shortness of breath. High risk patients were defined as those who were pregnant or immunosuppressed, and those who had chronic cardiopulmonary disease, diabetes or morbid obesity.

The first Victorian death occurred on 20 June 2009 when a Colac man died at Maroondah Hospital. On 23 June a second death occurred in Victoria, that of a 50-year-old woman who was immunocompromised, at the Peter MacCallum Cancer Centre. There was immense media interest. The Infectious Diseases Control department at the Peter MacCallum Cancer Centre had already done extensive emergency planning and preparation work for a flu pandemic. We were able to quickly convene a Swine Flu Working Group. The Working Group made use of the existing Peter MacCallum Cancer Centre organisational structure, and involved Infection Control and ICU physicians, the Director of Medical Services, the Clinical Director of Haematology, the Chief Nursing Officer, the HR director, Occupational Health and Safety and Media and Communications representatives. There was close liaison with the Victorian Minister for Health and the Health Department in trying to manage the fear that was in the community at the time. Our infection control strategy involved tracking of contacts and families, as well as closing ICU to new admissions and the setting up of a temporary satellite ICU in day surgery ward to take any new admissions. We had an infection control nurse at the hospital entry to ensure that none with symptoms entered “off the street”. Basic infection control measures including the use of masks, gowns and hand washing were implemented. Oseltamivir (Tamiflu) was given to staff and patients at risk.

Working closely with the Department of Health, we also put in place a structured communication strategy with the aim of framing messages in a way that was understandable to the public and not alarmist. We used the hospital’s infection control intranet pages and the email news (hospital wide weekly electronic bulletin) to keep people within the hospital informed.

Managing the media continued to be a major challenge. Shortly after we moved the intensive care unit to a temporary facility, there were news reports that the Peter MacCallum Cancer Centre was entirely locked down and closed for all new admissions. This caused further media interest, but was corrected at a subsequent media briefing. Throughout the process, Peter Mac’s strategy was to have clear media messages. The strategy was successful and the heat was taken out of the situation.

The Swine Flu peak in Australia occurred between June 1 and September 30, 2009. The final morbidity and mortality from Swine Flu in Australia totalled 37,642 cases and 191 deaths, which is low in the context of deaths from seasonal influenza mentioned previously.


Lessons Learned

Since the swine flu pandemic there has been much reflection. In an MJA editorial Professor Peter Collignon, Infectious disease physician at the Australian National University has identified three major lessons for the future:

Lesson 1:
By mid June 2009, there was a realisation that case-fatality rates here were low. Despite this knowledge, many costly interventions continued, including border control, widespread use of antivirals, school closures and contact tracing, but with little evidence that these made much difference to the overall rate or spread of the virus, (although they gave a high level of confidence to the general public). Appropriately, when it became obvious that the spread of the virus could not be controlled, the national pandemic plan was modified. A new phase, “PROTECT”, was adopted on 17 June, with a greater focus on treating and caring for those patients who were more vulnerable to severe outcomes.

Lesson 2:
The word “pandemic” can evoke needless fear and panic. This term would be best used when a virus not only spreads widely but also has increased virulence —this latter aspect is currently not considered in the World Health Organization definition. Virulence needs to be measured quickly and accurately.

Lessons 3:
Simple hygiene/barrier measures are more important than using antivirals. Staying away from work if ill is important. ICU networks are also very important. The antiviral strategy, which made little difference to the course of the disease, has been questioned. Given the costs involved of vaccines and antivirals, there is also some questioning of the links between doctors and drug companies. There is now an impetus for further investigation of better, longer acting vaccines.


Swine Flu in 2010 and 2011

On 10 August 2010, the WHO Director-General Dr Margaret Chan announced that the H1N1 influenza virus has moved into the post-pandemic period. However, localized outbreaks of various magnitudes are likely to continue. In 2010, H1N1 acted like seasonal flu and there was much less media interest.


Dr Bernard Street
Specialist in Medical Administration
Former Director of Medical Services, Peter MacCallum Cancer Centre
 

References
Taubenberger, JK, Morens DM, 1918 Influenza pandemic, 1918 Influenza: the mother of all pandemics, Emerging Infectious Diseases, Centers for Disease Control and Prevention, Vol 12 No1, Jan 2006.
Australian Government Department of Health and Ageing. Australian health management plan for pandemic influenza. Canberra: Commonwealth of Australia, 2008.
Colligan, Peter J, Swine flu: Lessons learnt in Australia, Medical Journal of Australia, Vol 192 No 7, pp. 364-365.



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